The aim of this work was to study the effects of different levels of salinity and compositions of irrigation water on the germination, growth and production of the herbaceous cotton plant - strain CNPA 2002/26 - Cluster Marrom Escuro. An experimental trial was carried out under greenhouse conditions at Embrapa - Cotton, Campina Grande - PB, using as a substrate a Neossolo, regossolo type with a sandy loam texture, originally classified as non-saline.

A 6 x 2 factorial design was adopted in a completely randomised design with three replications, studying the effect of 6 levels of electrical conductivity of the water (2. 0, 3.

5, 5. 0, 6.

5, 8. 0 and 9.

5 dSm-1) and 2 different compositions of irrigation water in terms of the Na+:Ca+2 ratio (9. 5:0.

5 % and 6:4 %, respectively) in the form of chloride. The following characteristics were analysed: germination percentage; plant height; number of leaves; leaf area; stem diameter; aerial, total and root phytomass; absolute growth rates, relative growth rate and leaf area ratio; number of bolls, average boll weight and seed cotton weight.

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